Satellite communications generally involve a plurality of ground stations that uplink to a plurality of satellites at defined frequencies, wherein the satellites downlink data to the ground stations, which then transmit the data to remote locations such as television or radio broadcast facilities and computer networks, among a plurality of other locations that may utilize the data for a variety of purposes. Although the types of satellite communications differ widely, there exist two primary techniques for establishing and maintaining communications between ground stations and satellites, namely, fixed frequency and fixed beam.
A fixed frequency satellite system coordinates uplink communications between ground stations and satellites by allocating a fixed frequency to a single ground station such that the ground station continuously uplinks at the fixed frequency. The satellite then directs a beam at the ground station, and the ground station continues to uplink at the fixed frequency while the satellite flies over the ground station and redirects the beam accordingly. Since the satellite must continuously redirect its beams to fixed ground stations on earth, the fixed frequency satellite system requires an extremely complex and expensive antenna.
A fixed beam satellite system, as the name implies, directs beams at the same direction towards the earth, and as the satellite flies over ground stations, the ground stations move from one beam to another. Current fixed beam uplink coordination techniques require that the satellite “track” each ground station, such that as the ground station moves from one uplink beam to another, the satellite must move a supporting demodulator to the correct beam. As a result, the satellite must reconfigure many demodulators quickly and frequently. Furthermore, demodulator fragmentation adds certain inefficiencies when multiple ground stations are positioned within a single beam, thus sharing the same demodulator bank, and are then positioned in separate beams, having different demodulator banks, as the satellite flies over the earth. Although it is possible to reduce demodulator fragmentation by having the satellite cause the ground station to change frequency, reliable satellite to ground station communications may be adversely affected. As a result, the management of individual users in realtime becomes complicated, and demodulator fragmentations causes inefficient use of resources onboard the satellite.
Accordingly, there remains a need in the art for a method of managing communications between ground stations and satellites that avoids the cost and complexity of fixed frequency antennas while improving the efficiency of uplinks between the ground stations and the satellites.